WASHINGTON (CNN) -- A pair of high-profile backers of Sen. Barack Obama have called on his rival, Sen. Hillary Clinton, to drop out of the race for the Democratic nomination for president.

Sen. Patrick Leahy, D-Vermont, issued the most unvarnished statement Friday, saying Clinton "has every right, but not a very good reason, to remain a candidate for as long as she wants to."

Sen. Chris Dodd of Connecticut, who sought the Democratic nomination for president himself but threw his support behind Obama after dropping out of the race in January, expressed a similar sentiment Thursday.

"I mean, if a person wants to stay in the race, stay in the race," he told the National Journal, a Washington magazine.

"But if you have enough people rallying behind what appears to be the likely choice, and I believe the choice is Barack Obama ... then I think you have to step up to the plate and say, 'Enough is enough.' We want this to be over with."

Larry Sabato, a professor of politics at the University of Virginia, said the Obama campaign was probably behind the remarks.

"Those things don't just happen," he said. "They must have gotten some encouragement from the Obama hierarchy. Senators like Leahy and Dodd can occasionally pop off, but not in a situation like this."